This state happens when your payment was sent to the network, but it didn't get a response back. So bluewallet doesn't know what happen, if it failed, if it succeed, etc.
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This payment usually enters in a "limbo" state that can go from 24h up to some days.
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Bluewallet will try every day to see if it can get a status of the payment.
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The payment gets unlock and available on your wallet again, when the timeout from the channels on each node it passed finished.
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Usually the timeout on each node is 24h, so imagine your payment had 3 hops and passed through 3 nodes, You will need to wait 62h to recover your funds.
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This is the worst known case at the moment on the network.